A method of implanting an implant species into a substrate at different depths is described. The method includes forming an implant mask over the substrate. The implant mask includes a first implant zone designed as an opening and a second implant zone designed as a block array. The implant species is implanted through the implant mask under an implant angle tilted against a block plane, such that a first implant area is formed by the implant species at a first depth in the substrate beneath the first implant zone and a second implant area is formed by the implant species at a second depth in the substrate beneath the second implant zone. The first depth is greater than the second depth.
Legal claims defining the scope of protection, as filed with the USPTO.
2. The method of claim 1, wherein the first lateral dimension is a minimum lateral dimension of the opening in a direction perpendicular to the block plane.
3. The method of claim 1, wherein the implant mask is used as a single mask to obtain the different depths.
4. The method of claim 1, wherein an upper surface of the implant mask adjacent the first implant zone is level with an upper surface of blocks of the block array.
6. The method of claim 5, wherein the different implant angle is the negative of the implant angle used in the prior implanting.
8. The method of claim 1, wherein the implant angle is between 5° and 45°, or 10° and 40°, or 15° and 35°, or 20° and 30°.
9. The method of claim 1, wherein the implant angle is within arctan(Np/t±15°), arctan(Np/t±10°), or arctan(Np/t±5°), or arctan(Np/t±2°), wherein t is the thickness of the implant mask, p is the block pitch of the block array and N is an integer equal to or greater than 1.
10. The method of claim 1, wherein the block pitch of the block array is equal to or less than 20 μm, 10 μm, 5 μm, 2 μm, 1.5 μm, 1.2 μm, 1.0 μm, 0.8 μm, 0.6 μm, 0.4 μm, 0.2 μm, 0.1 μm, or 80 nm.
11. The method of claim 1, wherein the thickness of the implant mask is equal to or greater than 0.1 μm, 0.2 μm, 0.5 μm, 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, 5.0 μm, 10 μm, or 20 μm.
12. The method of claim 1, wherein the implant mask is a photoresist.
14. The method of claim 1, wherein the implant mask is completely removed from the substrate between blocks of the block array.
15. The method of claim 1, wherein the first implant area and the second implant area are located at different depths under a lightly doped drain and/or a source structure of a semiconductor transistor.
16. The method of claim 15, wherein the semiconductor transistor is a nMOS device, and wherein the first implant area and the second implant area are n-type ESD implant areas.
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May 19, 2020
May 2, 2023
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